Heretofore, the speed of rotation of an object or a frequency of oscillation has been determined by a stroboscope. A stroboscope, more commonly termed a "strobe", may emit pulses of light at variable frequencies which are synchronized with the speed of rotation of the object or frequency of oscillation. When the object appears stationary under illumination of the strobe, the speed of rotation or the frequency of oscillation may be determined from the frequency of illumination of the strobe and the object may be visually inspected.
However, this technique is subject to inherent limitation. Intensity of light on an object degrades as a function of the square of the distance from the light source. The stroboscopic effect on the object can be lost in an environment of high ambient light. In fact, the strobe effect may be lost on a light emitting object. These factors limit the environment of usage of a strobe and the distance from the object under investigation, where it may effectively be used. Also, most strobes depend on the charging of a capacitor, or an external source for frequency of illumination. Since capacitor charging time and the rise and decay time of light sources is finite, the speed of a strobe is limited.
Accordingly, the present invention provides a new and improved system and method for determining the frequency of movement and visual inspection of a moving or changing object where the distance from the object and/or the ambient lighting conditions present little or no problem. In fact, it is preferred that the ambient lighting be high, and it may be augmented dependent upon the distance of the viewer from the object. The invention may also be utilized to determine the frequency of energization of a light emitting source.